U.S. patent application number 15/454935 was filed with the patent office on 2017-09-28 for cooling device and projection display device.
The applicant listed for this patent is JVC KENWOOD Corporation. Invention is credited to Mitsuharu FUKUDA.
Application Number | 20170277027 15/454935 |
Document ID | / |
Family ID | 58410144 |
Filed Date | 2017-09-28 |
United States Patent
Application |
20170277027 |
Kind Code |
A1 |
FUKUDA; Mitsuharu |
September 28, 2017 |
COOLING DEVICE AND PROJECTION DISPLAY DEVICE
Abstract
A cooling device includes a duct with one opened end and another
opened end; a fan disposed inside the duct, the fan being
configured to send air present inside the duct in an air-sending
direction; a heat sink disposed outside the duct, the heat sink
including a base part having an opposed surface opposed to a mouth
of the another end of the duct, and heat-sink fins including a
plurality of thin plates extending from the opposed surface along
the air-sending direction; a heat source in contact with the base
part; a heat pipe connected to the heat source or the heat sink;
and heat-pipe fins disposed between the fan and the one end of the
duct inside the duct, the heat-pipe fins including a plurality of
thin plates extending from the heat pipe along the air-sending
direction.
Inventors: |
FUKUDA; Mitsuharu;
(Yokohama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JVC KENWOOD Corporation |
Yokohama-shi |
|
JP |
|
|
Family ID: |
58410144 |
Appl. No.: |
15/454935 |
Filed: |
March 9, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 15/0266 20130101;
G03B 21/16 20130101; H01L 23/3672 20130101; F28D 15/00 20130101;
H01L 23/427 20130101; F21V 29/60 20150115; F28D 15/0275 20130101;
F28F 1/325 20130101; H01L 23/3677 20130101; H01L 23/467 20130101;
F21V 29/76 20150115 |
International
Class: |
G03B 21/16 20060101
G03B021/16; F28F 1/32 20060101 F28F001/32; F28D 15/02 20060101
F28D015/02; F21V 29/60 20060101 F21V029/60; F21V 29/76 20060101
F21V029/76 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2016 |
JP |
2016-059754 |
Claims
1. A cooling device comprising: a duct with one opened end and
another opened end; a fan disposed inside the duct, the fan being
configured to send air present inside the duct in an air-sending
direction, the air sending direction being a direction connecting
the one end of the duct with the another end thereof; a heat sink
disposed outside the duct, the heat sink comprising a base part
having an opposed surface opposed to a mouth of the another end of
the duct, and heat-sink fins comprising a plurality of thin plates
extending from the opposed surface along the air-sending direction,
the plurality of thin plates being apart from each other by a
predetermined distance; a heat source in contact with the base
part; a heat pipe connected to the heat source or the heat sink;
and heat-pipe fins disposed between the fan and the one end of the
duct inside the duct, the heat-pipe fins comprising a plurality of
thin plates extending from the heat pipe along the air-sending
direction, the plurality of thin plates being apart from each other
by a predetermined distance.
2. The cooling device according to claim 1, wherein the air-sending
direction is a direction from the one end of the duct toward the
another end thereof
3. The cooling device according to claim 1, wherein a part of the
heat pipe is disposed outside the duct.
4. The cooling device according to claim 1, wherein the base part
has a shape having a longitudinal direction, and the heat pipe is
connected to both ends in the longitudinal direction of the base
part.
5. The cooling device according to claim 1, wherein a plate-surface
direction of the heat-sink fins is in parallel with the
longitudinal direction of the base part.
6. A projection display device comprising a cooling device
according to claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from Japanese patent application No. 2016-059754, filed on
Mar. 24, 2016, the disclosure of which is incorporated herein in
its entirety by reference.
BACKGROUND
[0002] The present invention related to a cooling device and a
projection display device. For example, the present invention
relates to a cooling device that cools a light source of a
projector and a projection display device.
[0003] Semiconductor light sources such as lasers and light
emitting diodes (LEDs) have been increasingly used as light sources
of projectors. Since a semiconductor light source has a high
heat-generating density, it is cooled by using a radiator. Examples
of disclosed cooling structures include a structure in which a
radiator such as a heat sink is connected to a heat source and air
is sent to the radiator, and a structure for cooling a light-source
lamp by using a heat pipe.
[0004] Japanese Unexamined Patent Application Publication No.
2003-075081 discloses a projection display device 4 including a
lamp 5, which is a heat source, a heat-receiving block 42 to which
the heat source is connected, a heat sink 47 including a plurality
of radiation fins 48 disposed therein, and an exhaust fan 49 for
sending air to the heat sink 47 and thereby causing heat to radiate
therefrom as shown in FIGS. 8A and 8B. The projection display
device 4 disclosed in Japanese Unexamined Patent Application
Publication No. 2003-075081 transfers heat generated in the heat
source to the heat sink 47 through the heat-receiving block 42 and
heat pipes 43, and causes the transferred heat to externally
radiate from the heat sink 47 by using the exhaust fan 49.
[0005] Further, Japanese Unexamined Patent Application Publication
No. 2009-238948 discloses a heat sink equipped with fins, including
an axial fan with an air-inlet and an air-outlet formed therein,
first radiation fins disposed in the air-inlet, second radiation
fins disposed in the air-outlet, a heat pipe connecting the first
radiation fins with the second radiation fins, and a heat-receiving
block joined to the heat pipe. The heat sink equipped with fins
transfers heat generated in a heat source to the first and second
radiation fins through the heat pipe, and causes the transferred
heat to externally radiate from the first and second radiation fins
by using an exhaust fan 49.
[0006] It should be noted that when the size of radiation fins
disposed in a heat sink and/or a heat pipe is increased to increase
the cooling efficiency of the radiation fins, the radiation
efficiency does not improve when the size of the radiation fins
reaches a certain size and the radiation efficiency saturates
there. Further, when the size of radiation fins is increased, their
air resistance increases, thus causing a problem that even when the
volume of air is increased, the radiation cannot be improved in
accordance with the size of the radiation fins.
[0007] The present invention has been made to solve the
above-described problem and an object thereof is to provide a
cooling device and a projection display device capable of improving
the cooling performance of a heat source.
SUMMARY
[0008] A cooling device according to an embodiment includes a duct
with one opened end and another opened end; a fan disposed inside
the duct, the fan being configured to send air present inside the
duct in an air-sending direction, the air sending direction being a
direction connecting the one end of the duct with the another end
thereof; a heat sink disposed outside the duct, the heat sink
including a base part having an opposed surface opposed to a mouth
of the another end of the duct, and heat-sink fins including a
plurality of thin plates extending from the opposed surface along
the air-sending direction, the plurality of thin plates being apart
from each other by a predetermined distance; a heat source in
contact with the base part; a heat pipe connected to the heat
source or the heat sink; and heat-pipe fins disposed between the
fan and the one end of the duct inside the duct, the heat-pipe fins
including a plurality of thin plates extending from the heat pipe
along the air-sending direction, the plurality of thin plates being
apart from each other by a predetermined distance.
[0009] The above and other objects, features and advantages of the
present invention will become more fully understood from the
detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus are
not to be considered as limiting the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view showing an example of a cooling
device according to an exemplary embodiment;
[0011] FIG. 2 is a perspective view showing an example of a cooling
device according to an exemplary embodiment;
[0012] FIG. 3 is a cross section showing an example of a cooling
device according to an exemplary embodiment;
[0013] FIG. 4 is a side view of a cooling device according to an
exemplary embodiment;
[0014] FIG. 5A is a table showing an example of a simulation result
of a relation between each of disposition patterns of a heat sink,
a fan and heat-pipe fins, and the volumes of air and the thermal
resistance in that disposition pattern;
[0015] FIG. 5B is a table showing an example of a simulation result
of a relation between each of disposition patterns of a heat sink,
a fan and heat-pipe fins, and the volumes of air and the thermal
resistance in that disposition pattern;
[0016] FIG. 5C is a table showing an example of a simulation result
of a relation between each of disposition patterns of a heat sink,
a fan and heat-pipe fins, and the volumes of air and the thermal
resistance in that disposition pattern;
[0017] FIG. 6 is a perspective view showing an example of a cooling
device according to a comparative example 1;
[0018] FIG. 7 is a perspective view showing an example of a cooling
device according to a comparative example 2;
[0019] FIG. 8A shows an example of a projection display device in a
related art; and
[0020] FIG. 8B shows an example of a projection display device in a
related art.
DETAILED DESCRIPTION
Exemplary Embodiments
[0021] A cooling device according to an exemplary embodiment is
explained. The cooling device according to the exemplary embodiment
is, for example, a cooling device that cools a light source of a
projector. Firstly, a configuration of the cooling device according
to the exemplary embodiment is explained.
[0022] FIGS. 1 and 2 are perspective views showing the cooling
device according to the exemplary embodiment. FIG. 3 is a cross
section showing an example of the cooling device according to the
exemplary embodiment. FIG. 4 is a side view of the cooling device
according to the exemplary embodiment. In particular, FIG. 2 shows
the inside of a duct 50 shown in FIG. 1.
[0023] As shown in FIGS. 1 to 4, a cooling device 1 according to
this exemplary embodiment includes a heat sink 10, fans 20, a fan
mounting unit 25, heat pipes 30, heat-pipe fins 35, and a duct 50.
The cooling device 1 is a device that cools a heat source 60 in
contact with the heat sink 10, such as a light source having a high
thermal density. The material for the heat sink 10 and the
heat-pipe fins 35 may be aluminum, copper, or the like.
[0024] The duct 50 is a rectangular-tube shaped member with opened
ends (i.e., both ends of the duct 50 are opened). For example, the
duct 50 is a rectangular-tube shaped member in which the shapes of
its opened ends are rectangles. One of the opened ends of the duct
50 is referred to as "one end 51" and the other opened end is
referred to as "other end 52".
[0025] The fans 20 are disposed inside the duct 50. The fans 20
send air present inside the duct 50. For example, the fans 20 send
air in an air-sending direction that connects the one end 51 of the
duct 50 with the other end 52 thereof. For example, the air-sending
direction is a direction from the one end 51 toward the other end
52. The number of the fans 20 disposed inside the duct 50 may be
one or more than one. The fans 20 are, for example, a plurality of
propellers attached to their rotation shafts. The fans 20 send air
in a direction along (or in parallel with) the rotation shafts. The
fans 20 are disposed inside the duct 50 in such a manner that their
rotation shafts extend along the direction from the one end 51
toward the other end 52.
[0026] Here, for the sake of explanation, an XYZ-orthogonal
coordinate system is introduced in FIGS. 1 to 4. The direction in
which the fans 20 disposed inside the duct 50 send air is defined
as an X-axis direction. A direction on a plane orthogonal to the
X-axis direction, for example, the vertical direction is defined as
a Z-axis direction. A direction orthogonal to the X-axis and Z-axis
directions is defined as a Y-axis direction.
[0027] The fan mounting unit 25 is disposed on the periphery of the
fans 20 so as to surround the rotation shafts of the fans 20. Each
of the fans 20 rotates in an internal space surrounded by the fan
mounting unit 25. The fan mounting unit 25 is attached to the inner
peripheral surface of the duct 50. The fan mounting unit 25 shuts
out (i.e., blocks) the air flow inside the duct 50. As a result,
the air that is sent from the one end 51 of the duct 50 to the
other end 52 thereof passes through the parts in which the fans 20
rotate. That is, air that has flowed from the one end 51 of the
duct 50 to the inside of the duct 50 flows to the other end 52 of
the duct 50 through the parts which are not shut out (i.e., not
blocked) by the fan mounting unit 25 and in which the fans 20
rotate. Therefore, the area (i.e., the size) of the parts in which
the fans 20 rotate as viewed in the air-sending direction is
smaller than the cross section of the duct 50 in the direction
perpendicular to the air-sending direction.
[0028] The heat sink 10 includes a base part 10a having a first
surface 11 and a second surface 12. The second surface 12 of the
heat sink 10 is a surface of the heat sink 10 that is opposite to
the first surface 11. The longitudinal direction of the heat sink
10 is, for example, in parallel with the Y-axis direction. In such
a case, the longitudinal direction of the base part 10a is in
parallel with the Y-axis direction. The length of the heat sink 10
in the Y-axis direction and the length thereof in the Z-axis
direction are roughly equal to the length of the mouth of the other
end 52 of the duct 50 in the Y-axis direction and the length
thereof in the Z-axis direction, respectively. The first surface 11
of the heat sink 10 is opposed to the mouth of the other end 52 of
the duct 50. Therefore, the base part 10a of the heat sink 10 has
an opposed surface that is opposed to the mouth of the other end 52
of the duct 50 and located outside the duct 50. The heat sink 10
includes heat-sink fins 15 in addition to the base part 10a.
[0029] The heat-sink fins 15 include a plurality of thin plates.
The thin plates of the heat-sink fins 15 extend from the first
surface 11 of the base part 10a of the heat sink 10 toward the
mouth of the other end 52 of the duct 50. Each of the thin plates
of the heat-sink fins 15 is, for example, a thin-plate like member
having a plate surface whose longitudinal direction is in parallel
with the Z-axis direction. The thin plates of the heat-sink fins 15
have roughly the same shapes as each other. The length of the
heat-sink fins 15 in the Z-axis direction is roughly equal to the
length of the heat sink 10 in the Z-axis direction. Each of the
thin plates of the heat-sink fins 15 is disposed along a first
reference surface that is defined as a surface that intersects the
first surface 11 of the base part 10a of the heat sink 10 and the
mouth of the other end 52 of the duct 50. In the heat-sink fins 15,
the plurality of thin plates, which extend from the opposed surface
of the heat sink 10 in the air-sending direction, are apart from
each other by a predetermined distance. The first reference surface
is not limited to a planar surface. That is, the first reference
surface intersects the mouth of the other end 52 of the duct 50 and
continuously extends along the air-sending direction that is
determined based on the shape of the duct 50. Therefore, the first
reference surface is along (or in parallel with) the air-sending
direction.
[0030] The direction that is orthogonal to each of the thin plates
of the heat-sink fins 15 is the Y-axis direction. A direction
orthogonal to a plate surface is referred to as a "plate-surface
direction". The plate-surface direction of the heat-sink fins 15 is
in parallel with the longitudinal direction of the heat sink 10.
The plurality of thin plates of the heat-sink fins 15 are spaced
from each other in the plate-surface direction. Therefore, grooves
(i.e., gaps) between the thin plates of the heat-sink fins 15
extend in the Z-axis direction. Gaps between the thin plates of the
heat-sink fins 15 are along (or in parallel with) the air-sending
direction in the fans 20. That is, the plate-surface direction of
the heat-sink fins 15 is roughly perpendicular to the air-sending
direction.
[0031] The heat source 60 is disposed on the second surface 12 of
the base part 10a of the heat sink 10 so as to be in contact with
the base part 10a. For example, the heat source 60 is attached so
that it is closely (or tightly) in contact with the second surface
12 of the base part 10a of the heat sink 10. The heat source 60 is,
for example, a light source. More specifically, the heat source 60
is, for example, a laser light source or a semiconductor light
source. The number of the heat sources 60 may be one or more than
one. The heat source 60 is disposed at the center of the second
surface 12 of the base part 10a. Note that the heat source 60 is
not limited to the light source. That is, the heat source 60 may be
an electric device that generates heat such as a CPU (Central
Processing Unit).
[0032] The heat-pipe fins 35 are disposed inside the duct 50. The
heat-pipe fins 35 are disposed between the fans 20 and the one end
51 of the duct 50. The heat-pipe fins 35 include a plurality of
thin plates. Each of the thin plates of the heat-pipe fins 35 is,
for example, a thin-plate like member having a plate surface whose
longitudinal direction is in parallel with the Z-axis direction.
The thin plates of the heat-pipe fins 35 have roughly the same
shapes as each other. The length of the heat-pipe fins 35 in the
Z-axis direction is roughly equal to the length of the heat sink 10
in the Z-axis direction.
[0033] The plate-surface direction of the heat-pipe fins 35 is in
parallel with the Y-axis direction and in parallel with the
longitudinal direction of the heat sink 10. The thin plates of the
heat-pipe fins 35 are spaced from each other in the plate-surface
direction. Gaps between the thin plates of the heat-pipe fins 35
are along (or in parallel with) the air-sending direction in the
fans 20. That is, the plate-surface direction of the heat-pipe fins
35 is roughly perpendicular to the air-sending direction. Further,
the plate-surface direction of the heat-sink fins 15 and the
plate-surface direction of the heat-pipe fins 35 are roughly the
same as each other.
[0034] The heat pipes 30 include bent parts. For example, the heat
pipes 30 include curved parts. The number of the heat pipes 30 is
more than one. The heat pipes 30 are connected to the heat source
60 or the heat sink 10. The heat pipes 30 are connected to both
ends in the longitudinal direction of the heat sink 10 or the heat
source 60. For example, the heat pipes 30 are connected to both
ends in the longitudinal direction of the base part 10a. The heat
pipes 30 are joined to the side surfaces 13 and 14 of the heat sink
10 and buried inside the base part 10a of the heat sink 10.
[0035] The heat pipes 30 are connected to the center in the Z-axis
direction of the side surfaces 13 and 14. Further, the heat source
60 is disposed at the center of the second surface 12 of the heat
sink 10. Therefore, the place where the heat pipes 30 are in
contact with the heat sink 10 coincides with the place in the heat
sink 10 where the heat source 60 is disposed in the Z-axis
direction.
[0036] The heat pipes 30 that protrude from the side surface 13 of
the heat sink 10, which is located on the positive side in the
Y-axis direction, to the positive Y-axis direction are curved and
extend to the negative X-axis direction. Further, the heat pipes 30
are curved to the negative Y-axis direction and inserted into the
duct 50. Meanwhile, the heat pipes 30 that protrude from the side
surface 14 of the heat sink 10, which is located on the negative
side in the Y-axis direction, to the negative Y-axis direction are
curved and extend to the negative X-axis direction. Further, the
heat pipes 30 are curved to the positive Y-axis direction and
inserted into the duct 50. The heat pipes 30 inserted into the duct
50 are connected to the heat-pipe fins 35 disposed inside the duct
50. The heat pipes 30 pierce the plurality of thin films of the
heat-pipe fins 35 in the plate-surface direction. The parts of the
heat pipes 30 other than the parts piercing the heat-pipe fins 35
are disposed outside the duct 50. Therefore, the parts of the heat
pipes 30 are disposed outside the duct 50. Each of the thin plates
of the heat-pipe fins 35 is disposed along a second reference
surface that is defined as a surface that intersects the heat pipes
30 and the mouth of the one end 51 of the duct 50. In the heat-pipe
fins 35, the plurality of thin plates, which extend from the heat
pipes 30 in the air-sending direction, are apart from each other by
a predetermined distance. The second reference surface is not
limited to a planar surface. That is, the second reference surface
intersects the mouth of the one end 51 of the duct 50 and
continuously extends along the air-sending direction that is
determined based on the shape of the duct 50. Therefore, the second
reference surface is along (or in parallel with) the air-sending
direction.
[0037] In the case where the heat source 60 is a light source of a
projection display device and the light source is cooled by the
cooling device 1, the projection display device includes the
cooling device 1.
[0038] Next, an operation of the cooling device 1 is explained.
Firstly, the heat source 60, which is disposed on the second
surface 12 of the base part 10a of the heat sink 10, is started.
Heat generated in the heat source 60 is transferred to the heat
sink 10, with which the heat source 60 is in contact, through
thermal conduction (or heat transfer). Part of the heat transferred
from the heat source 60 to the heat sink 10 is radiated from the
heat sink 10 itself. Further, part of the heat transferred from the
heat source 60 to the heat sink 10 is radiated from the heat-sink
fins 15 disposed in the heat sink 10. Further, part of the heat
transferred from the heat source 60 to the heat sink 10 is further
transferred to the heat pipes 30 through thermal conduction.
[0039] Part of the heat transferred from the heat source 60 to the
heat pipes 30 through the heat sink 10 is radiated from the heat
pipes 30 themselves. Further, part of the heat transferred from the
heat source 60 to the heat pipes 30 through the heat sink 10 is
further transferred to the heat-pipe fins 35 through thermal
conduction. Then, the part of the heat transferred to the heat-pipe
fins 35 is radiated from the heat-pipe fins 35.
[0040] Meanwhile, the fans 20 are started before or after the start
of the heat source 60, or at the same time as the start of the heat
source 60. As a result, air is sent in the direction from the one
end 51 of the duct 50 to the other end 52 thereof inside the duct
50. That is, as shown in FIGS. 3 and 4, an air flow 71 occurs along
the direction from the one end 51 of the duct 50 to the other end
52 thereof.
[0041] Air taken from the mouth of the one end 51 of the duct 50
passes through the gaps between the thin plates of the heat-pipe
fins 35. The plurality of thin plates of the heat-pipe fins 35 are
spaced from each other in the plate-surface direction. Further, the
plate-surface direction is perpendicular to the air-sending
direction. That is, the gaps between the thin plates of the
heat-pipe fins 35 are along (or in parallel with) the air-sending
direction. Therefore, the air that has reached the heat-pipe fins
35 passes through the gaps between the thin plates of the heat-pipe
fins 35. As the air passes through the gaps between the thin plates
of the heat-pipe fins 35, heat is transferred from the heat-pipe
fins 35 to the flowing air. As a result, heat possessed by the
heat-pipe fins 35 is radiated.
[0042] The air that has passed through the gaps between the thin
plates of the heat-pipe fins 35 further passes through the parts in
which the fans 20 are rotating. In the parts other than the parts
in which the fans 20 are rotating in the duct 50, the air flow is
shut out (i.e., blocked) by the fan mounting unit 25.
[0043] The air that has passed through the parts in which the fans
20 are rotating further advances inside the duct 50. Then, the air
becomes an air flow 72 that exits from the mouth of the other end
52 of the duct 50. The base part 10a of the heat sink 10 is
disposed so as to be opposed to the mouth of the other end 52 and
the thin plates of the heat-sink fins 15 extend toward the mouth of
the other end 52. Therefore, the air that has exited from the mouth
of the other end 52 of the duct 50 passes though the gaps between
the thin plates of the heat-sink fins 15. The plurality of thin
plates of the heat-sink fins 15 are spaced from each other in the
plate-surface direction. Further, the plate-surface direction is
perpendicular to the air-sending direction. That is, the gaps
between the thin plates of the heat-sink fins 15 are along (or in
parallel with) the air-sending direction. Therefore, the air that
has reached the heat-sink fins 15 passes through the gaps between
the thin plates of the heat-sink fins 15. As the air passes through
the gaps between the thin plates of the heat-sink fins 15, heat is
transferred from the heat-sink fins 15 to the flowing air. As a
result, heat possessed by the heat-sink fins 15 is radiated.
[0044] The air that has passed through the gaps between the thin
plates of the heat-sink fins 15 is blown onto the first surface 11
of the base part 10a of the heat sink 10. Then, on the first
surface 11 of the base part 10a of the heat sink 10, part of the
air that has passed through the gaps between the thin plates of the
heat-sink fins 15 becomes an air flow 73 flowing in the direction
in which the grooves (i.e., gaps) between the thin plates of the
heat-sink fins 15 extend, i.e., in the positive Z-axis direction
and part of the air becomes an air flow 74 in the negative Z-axis
direction. Further, each time air passes (i.e., flows) toward the
positive and negative Z-axis directions, heat is transferred from
the first surface 11 of the heat sink 10 to the flowing air. As a
result, heat possessed by the heat sink 10 is radiated.
[0045] As described above, the heat sink 10, the heat-sink fins 15,
the heat pipe 30, and heat-pipe fins 35, each of which can radiate
heat by itself, can improve the cooling efficiency when there is an
air flow flowing therethrough. As a result, they can radiate heat
more effectively. Next, disposition patterns A to I of the heat
sink 10, the fans 20, and heat-pipe fins 35 are assumed and a
simulation result for a relation between each of the disposition
patterns, and the volume of air and the thermal resistance in that
disposition pattern is explained. FIGS. 5(a) to 5(c) are tables
showing examples of simulation results of relations between
disposition patterns of the heat sink 10, the fans 20 and the
heat-pipe fins 35, and the volumes of air and the thermal
resistances in these disposition patterns. Note that the volume of
air (hereinafter also referred to as an "air volume") means the
volume of air that moves per unit time in each disposition pattern,
and the thermal resistance means the thermal resistance of the heat
sink 10. Further, an increase in the thermal volume means a
decrease in the cooling efficiency.
[0046] A disposition pattern A shown in FIG. 5(a) corresponds to a
case where only the fans 20 are disposed inside the duct 50, in
which the ratio of the cross section of the fans 20 to the cross
section of the duct 50 perpendicular to the air-sending direction
(hereinafter, simply referred to as "the cross section of the duct
50") is adjusted to 1. The air volume in this state is defined as
100% and the disposition patterns A to C are compared with each
other. The disposition pattern B shown in FIG. 5(a) corresponds to
a case where the fans 20 are disposed inside the duct 50 and the
heat-pipe fins 35 are disposed on the air-discharge side of the
fans 20, in which the ratio of the cross section of the heat-pipe
fins 35 to the cross section of the duct 50 is adjusted to 1. In
this case, the air volume is 89%.
[0047] The disposition pattern C shown in FIG. 5(a) corresponds to
a case where the fans 20 are disposed inside the duct 50 and the
heat-pipe fins 35 are disposed on the air-intake side of the fans
20, in which the ratio of the cross section of the heat-pipe fins
35 to the cross section of the duct 50 is adjusted to 1. In this
case, the air volume is 87%.
[0048] Regarding the relation between the fans 20 and heat-pipe
fins 35, the air volume decreases when the heat-pipe fins 35 are
disposed irrespective of whether the heat-pipe fins 35 are disposed
on the air-intake side of the fans 20 or on the air-discharge side
thereof as shown in the disposition patterns A to C shown in FIG.
5(a). Further, the decrease in the air volume is smaller when the
heat-pipe fins 35 are disposed on the air-discharge side than when
the heat-pipe fins 35 are disposed on the air-intake side.
[0049] The disposition pattern D shown in FIG. 5(b) corresponds to
a case where only the fans 20 are disposed inside the duct 50, in
which the ratio of the cross section of the fans 20 to the cross
section of the duct 50 is adjusted to 0.60. The air volume in this
state is defined as 100% and the disposition patterns D to F are
compared with each other.
[0050] The disposition pattern E shown in FIG. 5(b) corresponds to
a case where the fans 20 are disposed inside the duct 50 and the
heat-pipe fins 35 are disposed on the air-discharge side of the
fans 20, in which the ratio of the cross section of the heat-pipe
fins 35 to the cross section of the duct 50 is adjusted to 1.
Therefore, the ratio of the cross section of the heat-pipe fins 35
to the cross section of the fans 20 is 1.65. In this case, the air
volume is 94%.
[0051] The disposition pattern F shown in FIG. 5(b) corresponds to
a case where the fans 20 are disposed inside the duct 50 and the
heat-pipe fins 35 are disposed on the air-intake side of the fans
20, in which the ratio of the cross section of the heat-pipe fins
35 to the cross section of the duct 50 is adjusted to 1. Therefore,
the ratio of the cross section of the heat-pipe fins 35 to the
cross section of the fans 20 is 1.65. In this case, the air volume
is 92%.
[0052] As shown in the disposition patterns D to F shown in FIG.
5(b), when the cross section of the duct 50 is increased, the
decrease in the air volume can be reduced in comparison to the
disposition patterns A to C. Further, similarly to the disposition
patterns A to C, the air volume decreases when the heat-pipe fins
35 are disposed irrespective of whether the heat-pipe fins 35 are
disposed on the air-intake side of the fans 20 or on the
air-discharge side thereof. Further, similarly to the disposition
patterns A to C, the decrease in the air volume is smaller when the
heat-pipe fins 35 are disposed on the air-discharge side than when
the heat-pipe fins 35 are disposed on the air-intake side.
[0053] The disposition pattern G shown in FIG. 5(c) corresponds to
a case where the fans 20 are disposed inside the duct 50 and the
heat sink 10 is disposed so as to be opposed to the mouth of the
other end 52 of the duct 50, in which the ratio of the cross
section of the fans 20 to the cross section of the duct 50 is
adjusted to 0.60. The air volume in this state is defined as 100%.
Further, the thermal resistance in this state is defined as 100%
and the disposition patterns G to I are compared with each
other.
[0054] The disposition pattern H shown in FIG. 5(c) corresponds to
a case where: the fans 20 are disposed inside the duct 50; the
heat-pipe fins 35 are disposed on the air-discharge side of the
fans 20; and the heat sink 10 is disposed so as to be opposed to
the mouth of the other end 52 of the duct 50. Further, the ratio of
the cross section of the heat-pipe fins 35 to the cross section of
the duct 50 is adjusted to 1. The ratio of the cross section of the
heat-pipe fins 35 to the cross section of the fans 20 is 1.65. In
this case, the air volume is 92%. Further, the thermal resistance
in this case is 109%.
[0055] The disposition pattern I shown in FIG. 5(c) corresponds to
a case where: the fans 20 are disposed inside the duct 50; the
heat-pipe fins 35 are disposed on the air-intake side of the fans
20; and the heat sink 10 is disposed so as to be opposed to the
mouth of the other end 52 of the duct 50. The ratio of the cross
section of the heat-pipe fins 35 to the cross section of the duct
50 is adjusted to 1. The ratio of the cross section of the
heat-pipe fins 35 to the cross section of the fans 20 is 1.65. In
this case, the air volume is 94%. Further, the thermal resistance
in this case is 104%.
[0056] As shown in the disposition patterns G to I shown in FIG.
5(c), when the heat sink 10 is disposed so as to be opposed to the
mouth of the other end 52 of the duct 50, the air volume decreases
when the heat-pipe fins 35 are disposed irrespective of whether the
heat-pipe fins 35 are disposed on the air-intake side of the fans
20 or on the air-discharge side thereof. However, the decrease in
the air volume is smaller when the heat-pipe fins 35 are disposed
on the air-intake side than when the heat-pipe fins 35 are disposed
on the air-discharge side.
[0057] The reason why the thermal resistances of the heat sink 10
are compared in the comparison among the disposition patterns G to
I is explained hereinafter. In general, the thermal resistance of
the heat pipes 30 is sufficiently smaller than that of the heat
sink 10 and heat is efficiently transferred to the heat-pipe fins
35. Therefore, the thermal resistance of the heat-pipe fins 35 does
not widely change. In contrast to this, the thermal resistance of
the heat sink 10 changes according to the change in the air flow to
the heat sink 10, which is caused by the flow-channel resistance
that occurs when air moves through the flow channel formed by the
gaps between the thin plates of the heat-pipe fins 35. Therefore,
the thermal resistances of the heat sink 10 are compared with each
other.
[0058] The reason why the changes in the air volume and in the
thermal resistance in the disposition pattern I are small is
explained hereinafter. Firstly, the disposition patterns G to I
differ from the disposition patterns A to F in regard to the
presence/absence of the heat sink 10. Next, among the disposition
patterns G to I, the disposition pattern I, in which the heat sink
10, which causes a flow-channel resistance, is disposed on the
air-discharge side of the fans 20, has a configuration in which the
fans 20 are disposed between the flow-channel resistance of the
heat sink 10 and the flow-channel resistance of the heat-pipe fins
35. In general, the air volume tends to decrease when there is a
flow-channel resistance on the discharge side of the fans 20. The
disposition pattern I is the only disposition pattern in which
there are flow-channel resistances on both of the air-intake side
and the air-discharge side of the fans 20. That is, in the
disposition pattern I, since the flow-channel resistance of the
heat sink 10 on the air-discharge side of the fans 20 as well as
the flow-channel resistance of the heat-pipe fins 35 on the
air-intake side are added, the balance between the air-intake side
of the fans 20 and the air-discharge side thereof is improved. It
is indicated that, as a result, the decrease in the air volume can
be reduced and the increase in the thermal resistance can also be
reduced. It should be noted that the among the disposition patterns
A to I, only the disposition patterns A and I have an excellent
balance between the air-intake side and the air-discharge side.
Therefore, among the disposition patterns B to I, the disposition
pattern I can achieve the movement of air that is closest to the
movement of air in the disposition pattern A.
[0059] Therefore, when a component that causes a flow-channel
resistance such as the heat sink 10 is disposed as in the case of
this exemplary embodiment, the cooling efficiency can be improved
by disposing the heat-pipe fins 35 on the air-intake side.
[0060] Further, in this exemplary embodiment, part of the heat of
the heat sink 10 is divided (i.e., transferred) to the heat-pipe
fins 35 by using the heat pipes 30. Then, the heat is radiated from
both the heat sink 10 and the heat-pipe fins 35. In this way, it is
possible to prevent the air volume from being reduced and improve
the cooling efficiency.
[0061] Next, advantageous effects of this exemplary embodiment will
be explained. However, before the explanation of advantageous
effects, comparative examples are explained. Then after that, the
advantageous effects of this exemplary embodiment are explained
while comparing them with those of the comparative examples.
[0062] FIG. 6 is a perspective view showing an example of a cooling
device according to a comparative example 1. As show in FIG. 6, a
cooling device 101 according to the comparative example 1 includes
a heat sink 10, fans 20, heat pipes 30, and heat-pipe fins 35.
However, the heat sink 10 has no heat sink fin 15. Further, the
heat-pipe fins 35 are disposed on the air-discharge side of the
fans 20.
[0063] As shown in FIG. 5, since the heat-pipe fins 35 are not
disposed on the air-intake side of the fans 20 in the cooling
device 101 according to the comparative example 1, the air volume
decreases and the cooling efficiency cannot be improved. Further,
the increase in the thermal resistance cannot be prevented. Since
no heat is radiated from heat-sink fins 15, the cooling performance
of the cooling device 101 is poorer than that in the disposition
pattern I according to the exemplary embodiment.
[0064] FIG. 7 is a perspective view showing an example of a cooling
device according to a comparative example 2. As show in FIG. 7, a
cooling device 102 according to the comparative example 2 includes
a heat sink 10, heat-sink fins 15, and fans 20. However, the
cooling device 102 according to the comparative example 2 has no
heat pipe 30 and no heat pipe fin 35. Therefore, the cooling device
102 cannot divide (i.e., transfer) the heat transferred to the heat
sink 10 to other radiating parts. Therefore, even when the size of
the heat sink 10 is increased, the radiation efficiency does not
improve when the size of the heat sink 10 reaches a certain size
and the radiation efficiency saturates there. Consequently, the
cooling efficiency cannot be improved.
[0065] Next, advantageous effects of the exemplary embodiment are
explained. The cooling device 1 according to this exemplary
embodiment divides the radiation part for radiating the heat
generated in the heat source 60 into the heat sink 10 connected to
the heat source 60 and the heat-pipe fins 35 connected to the heat
source 60 through the heat sink 10 and the heat pipes 30. In this
way, the cooling efficiency can be improved without increasing the
size of the heat sink 10. As a result, it is possible to prevent
the saturation of the radiation efficiency.
[0066] Further, in the cooling device 1, the heat-pipe fins 35, the
fans 20, and the heat sink 10 are arranged in this order from the
air-intake side. As shown in FIGS. 5(a) to 5(c), when there is a
structure (e.g., a flow-channel resistance) that interferes with
the air flow such as the heat-sink fins 15 near the mouth on the
air-discharge side of the duct 50, it is possible to prevent the
increase in the thermal resistance while preventing the decrease in
the air volume by disposing the heat-pipe fins 35 on the air-intake
side of the fans 20 rather than disposing them on the air-discharge
side of the fans 20. Further, when there is a flow-channel
resistance on the air-discharge side of the fans 20, it is possible
to efficiently send air while preventing the flow speed from being
reduced by disposing the fans 20 near the heat-sink fins 15. As
described above, in the cooling device 1, it is preferable that the
fans 20 are disposed between the heat-pipe fins 35 and the heat
sink 10, and hence the heat-pipe fins 35, the fans 20, and the heat
sink 10 are disposed in this order from the air-intake side.
[0067] The plate-surface direction of the heat-sink fins 15 is
roughly the same as the plate-surface direction of the heat-pipe
fins 35 and these directions are perpendicular to the air-sending
direction. As a result, it is possible to expedite (or increase)
the contact between the heat-sink fins 15 and the air and between
the heat-pipe fins 35 and the air, thus making it possible to
improve the cooling performance while preventing the decrease in
the air volume.
[0068] The number of the heat pipes 30 connected to the heat sink
10 is more than one, e.g., three. In this way, it is possible to
increase the amount of heat transferred from the heat sink 10 to
the heat-pipe fins 35.
[0069] Further, the heat pipes 30 are connected to both ends in the
longitudinal direction or the crosswise direction (or widthwise
direction) of the heat sink 10. More preferably, the heat pipes 30
are connected to both ends in the longitudinal direction of the
heat sink 10 rather than in the crosswise direction thereof. In
this way, the heat of the heat sink 10 can be uniformly transferred
to the heat pipes 30. As a result, compared to the case where the
heat pipes 30 are connected to only one end 51 in the longitudinal
direction of the heat sink 10, the imbalance in the cooling of the
heat source 60 can be prevented (or reduced) more effectively
especially when the heat source 60 is a light source having a high
thermal density.
[0070] In this exemplary embodiment, the plate-surface directions
of the heat-sink fins 15 and the heat-pipe fins 35 are both in
parallel with the longitudinal direction of the heat sink 10.
Therefore, the air that has exited from the mouth of the other end
52 of the duct 50 flows along the crosswise direction (or widthwise
direction) of the heat sink 10. As a result, the attenuation (i.e.,
the decrease) in the air volume can be prevented.
[0071] Note that the plate-surface direction of the heat-sink fins
15 may be in parallel with the Z-axis direction and the
plate-surface direction of the heat-pipe fins 35 may be in parallel
with the Y-axis direction. Further, the heat pipes 30 may be
connected to both ends in the Y-axis direction of the heat sink 10.
In such a case, the air-sending direction of the air that has
exited from the mouth of the other end 52 of the duct 50 is changed
to the Y-axis direction by the heat sink 10. Then, the air passes
through the gaps of the heat-sink fins 15 and exits from both ends
in the Y-axis direction of the heat sink 10. Note that since the
heat pipes 30 are connected to both ends in the Y-axis direction of
the heat sink 10, the air that has exited from both ends in the
Y-axis direction of the heat sink 10 comes into contact with heat
pipes 30. As a result, the air that has come into contact with the
heat pipes 30 causes heat in the heat pipes 30 to radiate therefrom
(i.e., absorbs heat from the heat pipes 30). Consequently, the
cooling efficiency can be improved even further.
[0072] Note that although the duct 50 has a rectangular-tube shape
extending in the X-axis direction in the above-described example,
the shape of the duct 50 is not limited to this shape. The duct 50
may have a cylindrical shape extending in the X-axis direction and
the mouth of the one end 51 of the duct 50 may have an arbitrary
shape. In such a case, the heat sink 10 and the heat-pipe fins 35
are shaped so that their shapes conform to the shape of the mouth
of the one end 51 of the duct 50. Further, although the duct 50 has
a tubular shape extending in one direction in the above-described
example, the duct 50 may have a curved tubular shape. In such a
case, the fans 20 send air so that the air-sending direction is
along (in parallel with) the shape of the duct 50.
[0073] Note that the first and second reference surfaces, based on
which the surface shapes of the heat-sink fins 15 and the heat-pipe
fins 35, respectively, are determined, may have such shapes that
they are continuously connected with respect to the shape of the
duct 50.
[0074] From the invention thus described, it will be obvious that
the embodiments of the invention may be varied in many ways. Such
variations are not to be regarded as a departure from the spirit
and scope of the invention, and all such modifications as would be
obvious to one skilled in the art are intended for inclusion within
the scope of the following claims.
* * * * *